#pragma once
#include <vector>
#include <unordered_set>

using namespace std;

namespace containsDuplicate
{
	class Solution {
	public:
		bool containsDuplicate(vector<int>& nums) {
			unordered_set<int> data;
			for (int i = 0; i < nums.size(); i++)
			{
				if (data.find(nums[i]) != data.end())
				{
					return true;
				}
				data.insert(nums[i]);
			}
			return false;
		}
	};
}